Over The Counter Drugs For Constipation

The common OTC medications for constipation have been grouped as follows: 1–4

Bulk-forming agents 
Lubricating agents
Stool softeners
Osmotic laxatives

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Bulkforming Agents

Bulk-forming agents absorb water and help in the formation of soft, bulky stool, which prompt normal contraction of the muscles of the intestine leading to defecation. Some of these agents along with their trade names are as follows:

  • Methylcellulose (Citrucel)
  • Polycarbophil (FiberCon)
  • Psyllium (Metamucil)


  • Constipation
  • Long term preventive treatment

Dosage: Oral dose of 15–60 g/day along with at least 8 glasses of water in a day.


  • Allergy to the drug
  • Obstruction in the intestine

Interactions: These agents prevent absorption of medications that are taken within 30 min of the bulk forming agent 

Lubricating Agents

These agents tend to lubricate intestine by decreasing the absorption of water from intestine thereby facilitating easy passage of stool.
Some of the drugs under this group are:

  • Glycerin (as a suppository)
  • Mineral oil

Indications: Short term constipation

Dosage: Oral dose of 15–45 mL (mineral oil)
Contraindications: Allergy to the drug.
Interactions: These agents prevent absorption of certain medications such as warfarin, oral contraceptives, and fat-soluble vitamins.

Stool Softeners

The stool softeners also known as emollient laxatives cause addition of water and fat to stool which softens it and allows strain-free movement.

The common drugs are:

  • Docusate sodium (Colace)
  • Docusate calcium (Surfak)


  • Short-term constipation
  • For individuals with anal fissures or hemorrhoids

Dosage: Oral dose of 50–360 mg/day.


  • Allergy to the drug
  • Short and severe pain in the abdomen
  • Vomiting

Interactions: Prevents absorption of certain medications such as warfarin.

Osmotic Laxatives

These agents cause secretion of water into the intestine by osmosis and thereby soften the stool to ensure its easy passage.

The commonly used drugs and their dosages are as follows:

  • Lactulose: 15–60 mL/day
  • Magnesium citrate:0.5–1 bottle (296 mL)/day
  • Magnesium hydroxide (Milk of Magnesia): 30–60 mL once-daily
  • Polyethylene glycol 3350 (Miralax): Once-daily
  • Sodium biphosphate (Phospho-Soda): 20–45 mL daily
  • Sorbitol: 30–150 mL daily

Indications: Long-term constipated individuals who do not respond to dietary fibre supplementation.


  • Allergy to the drug
  • Decreased or absent urine formation (Sorbitol is contraindicated)
  • Colitis, bowel perforation, gastric retention or bowel obstruction (Miralax)

The osmotic agents should be used carefully in individuals with congestive heart failure and long-term kidney disorders.

Interactions: Prevents absorption of certain medications, which are taken orally.


These agents initiate rhythmic contractions of the muscles of the intestine muscles to eliminate stool.

The common drugs and their dosages are:

  • Bisacodyl (Dulcolax): 5–15 mg daily
  • Cascara sagrada: 5 mL/L tablet once-daily
  • Castor oil: 15–60 mL once-daily
  • Senna (Senokot): 2 or 4 tablets once/twice-daily

Indications: Short-term constipation.


  • Allergy to the drug
  • Vomiting or vomiting sensation
  • Bleeding from the gastrointestinal tract
  • Appendicitis
  • Congestive heart failure
  • Stool impaction

Interactions: Prevents absorption ofcertain medications, which are taken orally.

Written by: Healthplus24 team
Date last updated: March 21, 2012

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